The Mechanism of the Solar Dynamo Governing Space Climate and Space Weather

Long-term and short-term variations in the magnetic activity of the sun profoundly influence space weather on Earth and space climate. Past solar activity shows periods of extended minima, which are still not well understood. This project will address questions related to the cause and characteristics of grand minima in solar activity, how the character of solar activity changes during these periods, and whether these changes can be modeled/predicted. The methodology uses a combination of observations of sunspot numbers, isotope time series, machine learning techniques, and numerical modeling. The results will provide constraints on the solar dynamo that generates the changing magnetic fields on the sun, which causes space weather. The broader impacts will be to improve our understanding of our space climate and space weather that affect our ground-, air- and space-based technological systems. This project supports an early career researcher. The overarching scientific question is to decipher the physics underlying short- and long-term behavior of solar magnetic activity both in temporal and spatial domains, and to constrain the solar dynamo model. Direct and indirect solar activity indices, such as sunspots and 10Be and 14C isotope records at annual and decadal resolutions, combined with machine learning techniques and numerical simulations, will be used to reconstruct annual sunspot numbers throughout the past 11,000 years covering the Holocene. The expected results include better characterization of the length of the solar cycle before, during, and after past grand solar minima; improved understanding of the nature and occurrence characteristics of grand minima and maxima; and observational constraints on solar dynamo models to decipher the underlying physical mechanisms that lead to the observed variations in solar activity. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.